I. Field of the Invention
This invention relates to slab lasers and, more particularly, to a slab active lasing medium therefor having an improved design.
II. Description of the Prior Art
Optically-pumped lasers employing an active lasing medium having a cylindrical configuration or, alternatively, a slab configuration are both known in the art. Conventional slab lasers have the end faces of the slab cut at Brewster's angle to minimize intra-cavity reflection losses. The slab is situated within an optical resonant cavity and the laser resonator modes of the laser wave energy traveling through the slab propagate in a zigzag manner down the length of the slab by total internal reflection. Total internal reflection results from the fact that the internal angle of incidence at the slab boundary of this propagating wave energy is always very much larger than the critical angle of incidence for the active lasing medium material comprising the slab. A typical example of the material comprising the active lasing medium is neodymium glass (Nd/glass). Nd/glass exhibits an index of refraction that is about equal to 1.5, a Brewster angle .theta..sub.B of about 56.degree., an angle of incidence i.sub.B of about 67.degree., and a critical angle .theta..sub.C of about 42.degree..